This invention generally relates to an electric component such as, for example, a trimmer capacitor, a variable resistor or a rotary switch, and more particularly, to the electric component of a type having a rotary mechanism.
A prior art rotary electric component such as, for example, a trimmer capacitor including a rotor and a stator comprises a head shaft having its head rigidly connected to the rotor for rotation together therewith and rotatably extending through the stator or a combination of stator and support base of synthetic resin, the free end of the shaft opposite to the head being connected to a terminal member located on one side of the stator remote from the rotor. For connecting the free end of the shaft to the terminal member, the free end of the shaft is bored to form an axially inwardly extending recess that defines a thin-walled annular end therearound. This thin-walled annular end of the shaft is, after having been passed through a bearing opening in the terminal member, crimped so as to expand radially outwardly thereby avoiding any possible separation of the terminal member from the shaft.
In this construction, that portion of the terminal member where the bearing opening is defined is so shaped as to provide a spring washer which, in the assembled condition, exerts an urging force to bring the rotor and the stator close together.
This type of rotary electric component is usually mounted as an electric component part on a printed circuit board with its terminal members soldered to printed wirings by the use of a dip-soldering method or a reflow-soldering method. In view of this, it has now been found that, when the dip-soldering or reflow-soldering method is applied to the prior art rotary electric component of the construction described above, the rotary electric component itself tends to be warmed to such an elevated temperature as to result in the thermal deformation of the radially outwardly crimped, thin-walled annular end of the shaft. Once this happens, a loss of firm connection of the shaft to the terminal member is prone to occur with consequent reduction in torque of the rotor.